The present invention relates to body insertable medical devices, and more particularly to catheters for retrieving and removing unwanted objects from blood vessels and other body lumens.
A wide variety of treatment and diagnostic procedures involve the use of devices inserted into the body of a patient, either for temporary use or for permanent implantation. Among these devices are prostheses or stents of the radially self-expanding and plastically expandable types, grafts, combination stent/grafts, braided occlusion devices and embolization coils. Typically these devices are delivered endovascularly on catheters, to be released at the intended treatment site. Many of these devices are small and fragile. Further, because they cannot be viewed directly during deployment, radiopaque fluids, markers and other aids are used to assist transluminal delivery, initial positioning, release of the device, confirmation of position after release, and perhaps a repositioning if an initial positioning is not correct. Further steps, e.g. expanding the device through inflating a balloon, may be required.
In short, deployment of body insertable devices requires considerable skill and involves multiple stages, each involving a risk of the device releasing prematurely or breaking loose to become an unwanted foreign object in the vessel. The need to recover an insertable device might arise due to a fault in the insertable device, improper selection (e.g. wrong type or size), a fault in the deployment device, or improper technique. As the use of body insertable devices increases, so does this risk.
One known approach to retrieving or recovering such devices is disclosed in U.S. Pat. No. 5,171,233 (Amplatz et al). An intravascular snare includes an elongate catheter, with a loop-shaped segment of a wire extending from a distal end of the catheter, oriented at an angle of 45 degrees or more from the axial direction. The loop or snare can be formed of a superelastic shape memory alloy, so that it can be collapsed for intravascular delivery and opens into an unrestrained configuration upon emerging from the distal tip of the catheter. While a device of this type is capable of recovering insertable devices and other unwanted foreign matter, it also involves the risk of dislodging an object before it has been securely grasped. Then, blood flow may carry the object downstream into a narrower, more tortuous portion of the vessel, increasing the difficulty of recovery, and in some cases rendering recovery impossible without major surgery.
Therefore, it is an object of the present invention to provide an intraluminal retrieval device capable of retrieving a foreign object from a body lumen, with virtually no risk of the object becoming prematurely dislodged and carried out of reach by the flow of blood or another fluid.
Another object is to provide a retrieval device with a lumen isolation structure to confine an object for retrieval, while also more positively securing the retrieval device at a desired position along the body lumen.
A further object is to provide an intraluminal retrieval device that facilitates the use of aspiration and irrigation as effective options to snares or other coupling devices to remove objects from vasculature.
Yet another object is to provide a process for retrieving an object from a body lumen, in which the object is confined to a particular segment of the body lumen, before it is conveyed to a retrieval chamber for eventual removal from the body lumen.